WHO Drug Information Vol. 24, No. 4, 2010

WHO Drug Information Vol. 24, No. 4, 2010Consultation Documents294 nm and at about 327 nm. The specific absorbance (A 1% ) at 294 nm is between876 and 948.1 cmD. Determine the specific optical rotation (1.4) using a 30 mg/ml solution dissolved in amixture of 10 volumes of methanol R and 40 volumes of dichloromethane R andcalculate with reference to the anhydrous substance; [α]20 °C = -12° to -11°.[Note from Secretariat: suitability of carrying out the Optical rotation test in methanolunder investigation and corresponding limits to be confirmed.]Heavy metals[Note from Secretariat: suitable test for heavy metals under investigation.]Sulfated ash (2.3). Not more than 1.0 mg/g.Water. Determine as described under 2.8 Determination of water by Karl FischerMethod, Method A. Use 1.0 g of the test substance. The water content is not less than21 mg/g and not more than 27 mg/g.Impurity ACarry out the test as described under 1.14.1. Thin layer chromatography, using silicagel R6 as the coating substance and a mixture of 10 volumes of glacial acetic acid R,10 volumes of water R and 20 volumes of ethyl acetate R. Apply separately to theplate 10 l of each of the two following solutions in the dissolution solvent prepared bymixing 10 volumes of methanol R and 40 volumes of dichloromethane R. For solution(A) use 50 mg of Levofloxacin per ml. For solution (B) use 0.1 mg of levofloxacinimpurity A RS per ml. After removing the plate from the chromatographic chamber,allow to dry in air. Examine the chromatogram in ultraviolet light (254 nm).Any spot obtained with solution A corresponding impurity A is not more intense thanthe principal spot obtained with solution B.Other related substancesPrepare fresh solutions, protected from light and perform the tests without delay.Carry out the test as described under 1.14.4 High-performance liquid chromatography,using a stainless steel column (15 cm x 4.6 mm), packed with particles of silica gel thesurface of which has been modified with chemically bonded octadecylsilyl groups(5 µm). (Symmetry 150 x 46 mm (5 µm) is suitable.)Maintain the column temperature at 45 °C.Prepare the mobile phase as follows: dissolve 4.0 g of ammonium acetate R and 7.0 gof sodium perchlorate R in water R and dilute to 1300 ml; adjust to pH 2.2 with phosphoricacid R and add 240 ml of acetonitrile R.Prepare the following solutions in the dissolution solvent prepared in mixing 10 volumesof acetonitrile R and 60 volumes of water R.For solution (1) dissolve 10 mg of Levofloxacin in the dissolution solvent and dilute to50.0 ml with the same solvent. For solution (2) dilute 1.0 ml of solution (1) to 50.0 ml339